1. Field of the Invention
This invention relates generally to GPS (Global Positioning System) and, more particularly, to a self-surveying relative GPS weapon guidance system.
2. Discussion of the Related Art
Various weapon guidance systems are in use today. These weapon guidance systems use various techniques to guide weapons to designated three-dimensional points in space. The guidance techniques currently utilize technologies such as GPS, laser, radar and cameras or any combination thereof. In each of the techniques mentioned above, however, there are various accuracy limitations inherent throughout the systems. Thus, if any one of the accuracy limitations in the systems can be reduced, the overall accuracy of an entire guidance system can be improved.
For example, some weapon guidance systems will utilize either a manned or an unmanned aircraft to pass over multiple targets. As the aircraft passes over these targets, the aircraft will identify the location of the targets using radar such as synthetic aperture radar (SAR) or laser radar (LADAR) in combination with a GPS receiver. This aircraft can then provide aim points in GPS coordinates of the various targets to multiple attack weapons. Other weapon guidance systems may eliminate the aircraft and merely use a guided weapon with a terminal seeker. The terminal seeker may consist of the SAR or LADAR in combination with the GPS receiver positioned within the guided weapon itself.
In each of the above scenarios, however, there will be inherent errors associated with the aircraft guidance, GPS location, radar error and attack weapon guidance. By taking the root sum square (RSS) from each of the individual errors, the specific overall error of the guidance system can be calculated. Accordingly, it can be observed that the overall system accuracy will be increased by reducing any one of the inherent errors in the system.
What is needed then is a weapon guidance system having an overall reduced accuracy error so that the attack weapons can be delivered more accurately. This will, in turn, provide a more accurate weapon guidance system which is extremely versatile in many types of situations. Moreover, such a system could eliminate the need for terminal seekers in each guided weapon, thereby reducing cost. It is, therefore, an object of the present invention to provide such a weapon guidance system.